It is common practice to provide on plug and receptacle type electrical connectors keying means which permits a keyed pair of connector parts to be mated with each other and which prevents the mating of either of the keyed parts with another connector part not having the same keying code. Keying systems are desirable when it is necessary to mount several identical connector assemblies close to each other for the reason that, in the absence of suitable keying means, a technician might mismate the connector parts with each other and thereby render the circuits inoperable or such mismating might cause serious damage to the circuits.
There are many keying systems in use and, while they all perform the keying functions adequately, most are subject to some objections. For example, a keying system for a connector assembly can be produced on the connector assembly at the time of manufacture by forming complementary keys and keyways on the two parts of the connector assembly. This is an effective keying system since it cannot be changed by a technician; however, it is necessary to change the manufacturing process from one connector assembly to another to produce the different keying systems. This type of keying system is relatively expensive in that it significantly increases the manufacturing cost of the connector for the reason that the connectors produced on a long production run are not identical to each other but differ from each other in respect to the locations of the keys and keyways.
It is also common practice to use a plug in one of the terminal-receiving cavities in one of the connector parts. The complementary connector part is keyed to the connector part having the plugged cavity if no terminal is mounted in the corresponding cavity of the complementary connector part. This keying system is highly effective but it results in the loss of one of the terminals in each connector part and thereby reduces the capacity of the connector assembly to carry electrical circuits.
The present invention is directed to the achievement of a keying system which does not result in the loss of any of the terminals in the connector, which does not require changing the manufacturing steps from one connector part to an identical connector part, and which permits the technician to establish the keying system at the time of installation of the connector on the equipment on which it is used. The invention is further directed to the achievement of a keying means on connectors which can be changed, if required, without damage to either of the connector parts.
An electrical connector assembly in accordance with the invention comprises a plug part and a receptacle part, the receptacle part having a hood portion which surrounds, and extends beyond, the mating face of the receptacle part. When the plug is coupled to the receptacle part, forward portions of the plug housing are received within the hood of the receptacle. The keying means comprises a key which can be assembled to the plug part by merely sliding the key into one of several grooves provided on the surface of the plug part. The hood of the receptacle has a plurality of latent slots therein in the form of thin-walled elements which can be removed with any available sharp tool. The keyway is thus produced by simply cutting out the appropriate thin-walled element of the receptacle hood and the keyway then will receive the key which has been mounted on the plug. If it is desired to change the keying arrangement for a connector assembly, a slot in the receptacle hood can be closed by inserting a key into the slot in the hood.